you are fortunate indeed that he is your former lawyer. Do you how know how many lawyers I've had dealings with? I don't know if you have been in Thailand as long as I have but if I had believed every rumour I ever heard about changing government policy that never ended up on the statute books I'd be a multi-millionaire. I'll give you an example. Many years ago when I was a marketing director for a property company I got a phone call from someone who claimed to be on the government committee that was going to change policy that would disallow foreigners from becoming directors on companies that owned land. Did it ever happen? What do you think? Apart from the fact that you are ignoring dual taxation treaties why did your lawyer pick 35% out of the hat. Why not the normal withholding tax of 15%. Beware of what Thai lawyers tell you or anyone else for that matter. Instead of spreading spurious rumours why don't you just wait and see what happens. Learn and understand.
One transaction a year is all that is necessary to keep your bank account active. So just use your banking app to do a small deposit or transfer. But beware, if you neglect to do so and the account becomes inactive you can only activate it again by physically visiting a branch office with your passport.